Cell and gene therapy products must be tested for sterility, stability, purity and potency. In addition, its important to test clinical cell thearpy products for identity, consistency and comparability. Testing cellular and gene therapies is challenging. These therapies are generally collected from a single person so the quantity of material available to test is limited. They are typically transfused immediately after they are produced so there is a very limited amount of time to complete the assays. Many of these therapies are complex cells that have multiple functions. The cell functions that are critical to the clinical effectiveness of these therapies are often not known. Traditionally, analytic assays such as flow cytometery, ELISA, ELISPOT and cell culture have been used to analyze cellular and gene therapies. While these assays have proven to be very useful, the number and types of factors that can be analyzed with these assays is limited. We have been investigating the use of gene and micro RNA expression assays for the analysis of cellular therapies. These assays can require the use of only small quantities of cells and can be used to test up to 44,000 factors at one time. We have been testing the ability of global gene and micro RNA expression profiling to determine the utility of these assays for assessing the stability, purity and potency of cellular therapies. We have shown that gene expression profiling can detect changes in stored cells and detect differences between peripheral blood leukocytes (T cells, B cells and monocytes) and hematopoietic stem cells. Gene expression profiling has also been able to detect differences between immature and mature dendritic cells (DCs) and has been useful for comparing mature DCs produced using different combinations of maturation agents. We will soon begin analyzing clinical DC products to compare gene expression with clinical outcome in order to identify biomarkers that might be useful of consistency, stability, identity and potency testing. We have assessed global gene expression profiles of T Rapamycin cells that are given to hematopoietic stem cell transplant patients to improve stem cell engraftment and prevent disease relapse. The studies have revealed several biomarkers which may be useful for identity, consistency and potency testing of these products. We are now comparing T Rapamycin product biomarkers with clinical outcome measure to identify potency biomarkers. We have been investigating sensecence of bone marrow stromal cells (BMSCs) and have found a 24 gene set that predicts BMSC time in culture as measured by population doublings. We have also been seraching for biomarkers expressed by peptide-plused mature dendrtic cells whose expression coorelates with clinical effectiveness.